Thousands of Mayflies Are Back in Iowa: What to Expect

Well, it's officially mayfly season again in Iowa!

The often annoying but completely harmless bugs that live only for a day or two when they reach adulthood.

An ever-present summer pest is back to enjoy a few short summer days in Iowa and around the U.S.

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So far in 2025, we've already seen a "biblical" amount of mayflies visit a youth baseball game in the Quad Cities.

Summer 2025: Where We're Seeing the Mayflies

So far, we've seen plenty of these buggers in Eastern Iowa, largely because they've hatched in and around the Mississippi and flown there way west.

We Are Iowa reported that a swarm of bees raced from the Mississippi River near Burlington to as far west as Marengo, approximately 50 miles, and even appeared near Des Moines and Pleasant Hill.

There were so many flying together, they even showed up on a National Weather Service radar in Davenport.

READ MORE: Iowa Weather Records Through the Years

So far, most of the mayflies have skirted south of Cedar Rapids, but in the past, as documented by meteorologist Nick Stewart, they weren't shy about visiting the Corridor.

Iowa is far from alone when it comes to seeing the mayflies invasion up close. Our sister station in Central Michigan recently shared a story about the massive mayfly storm that's hit them.

The Simple, Short Life of a Mayfly

Mayflies emerge in massive numbers from river-bottom nymphs (aquatic larval stage) during their short adult lives to mate, often lasting just minutes to a couple of days.

Their annual emergence typically happens in late May and can run through early July, when water temperatures and river conditions are just right.

As mentioned earlier, once adulthood is reached, the bugs die very quickly. Mayflies aren't a serious nuisance to farmers and do not threaten crops.

Adults don’t even eat. Nothing but mating drives them.

Mayflies Are Annoying, But...

Yes, they are quite messy. But, they are natural, and a sign of healthy waterways in Iowa and wherever they appear.

READ MORE: An Iowa-Based Department Store Called One of the Best in U.S.

The mass hatch is an annual show of nature. If you’re out near the Mississippi or elsewhere close to rivers, be ready for mayfly magic, and the occasional messy cleanup afterward...

Mayflies aren't too snobby, but these Iowa towns are (according to AI).